This invention relates generally to a carrier vehicle and particularly to a steering system for such a vehicle.
Vehicles having multiple steering modes are not in themselves new and several patents disclose vehicles of this general type. Such vehicles include various improvements on the multiple mode principle. For example, one such patent discloses a hydraulic steering system having a selector valve actuated by solenoids and controlled by a switching system which prevents a mode change unless the front and rear wheels are in parallel alignment with the longitudinal axis of the vehicle. Several other patents disclose variations on this valve switching, however, none of them discloses a simple visual indicator system capable of eliminating problems inherent in steering mode change.
Vehicles incorporating multiple mode steering systems tend to provide linkage which turns the wheels directly about a vertical swivel axis. The result of this has been that such mechanism is essentially structurally organized in one horizontal plane and this arrangement, while suitable for straddle type vehicles, is a distinct disadvantage for low profile vehicles suitable for use in underground mines.
Although the advantages of providing four-wheel steering on self-propelled vehicles are well recognized, the advantages of providing four-wheel control on trailer vehicles, and more particularly on a train of towed vehicles, do not appear to be appreciated. Certainly, the systems referred to above are generally far too complicated to be economical or feasible for utilization in a trailer vehicle.
The above disadvantages and limitations inherent in known steering systems have been overcome by the present device in a manner neither disclosed or suggested in prior vehicles of this type.